The advent of cubicles for use in an office environment has generated a need for portable, lightweight, and versatile partitions. One response to this need was the creation of interlocking panel systems, in which a number of small modular panels are attached to a structural frame that forms the walls of the cubicle. Each individual modular panel is generally comprised of an individual metal frame or base around which, or over which, is stretched or secured a decorative fabric layer. In many instances, the decorative fabric layer is a flat woven fabric, chosen to complement the décor of the office setting, which is adhered to the surface of the modular panel.
Such office panels are subject to stringent performance requirements, including industry standards for flame retardance and practical standards for strength, stiffness, surface properties, and acoustical properties.
Flame retardance is perhaps the most important physical characteristic of these panels, because of safety considerations and industry requirements. To meet industry standards, office panels must meet Class A (or Class I) flammability requirements, including a Flame Spread Index score of 25 or less and a Smoke Developed Index score of 450 or less. The flame spread index is a number that relates to the rate of flame propagation or spread over time. The smoke developed index is a number that relates to the relative amount of smoke generated during the test for surface burning characteristics (i.e., flame spread). Both the Flame Spread Index and the Smoke Developed Index are calculated when samples are evaluated according to ASTM E84-04, entitled “Standard Test Method for Surface Burning Characteristics of Building Materials.” In order to meet these requirements, most office panels include a fiberglass panel, which is added to enhance the flame retardance of the office panel. Fiberglass is well-known for its flame retardant properties, making it the current material of choice for these applications.
However, the manufacture and use of fiberglass panels raises several potential health and environmental issues. First, concerns exist about the health and wellness of persons exposed to fiberglass during manufacturing and installation of such panel systems. While manufacturers take measures (for example, providing ventilation and personal protective equipment) to ensure that workers are not exposed to inhalation risks or irritation from skin exposure during the manufacture and installation process, a better solution would involve the elimination of fiberglass from the modular panels.
A second problem associated with fiberglass is that it is generally not recycled. The recycling of fiberglass is very energy intensive and few products use recycled fiberglass content. Not only is the fiberglass itself generally not recycled, but panels containing fiberglass and other fiber or resin types are difficult to recycle due to their mixed content. Because manufacturers currently face increasing pressures to produce environmentally friendly products that may be reusable or recyclable at the end of the product's life, the industry is seeking a product that may be recycled but that exhibits the flame retardant performance of fiberglass.
Another issue to be addressed by any product introduced into this market is the need for the composite panel to be both strong and stiff, so that when the composite is oriented vertically into a frame, it does not bend or warp. The term “strength” refers to the composite's ability to resist permanent deformation (e.g., bending or bowing) that falls short of a complete structural failure. The term “stiff” refers to the composite's ability to resist non-permanent deformation (e.g., bending or bowing) under a load. When used in office panels, the present composites are positioned in a vertical orientation and must maintain their physical integrity, resisting breakage, buckling, bending, curling, warping, sagging, etc. Such properties may be similarly important for applications, other than the modular panels described herein.
Yet another desirable property for composites used in office panels is for the composite to have a smooth exterior surface on at least one side. Because a textile fabric is attached (e.g., bonded or glued) to the surface of the composite panel, it is necessary that such surface be stiff, smooth, and free from protrusions, bumps, or bulges that would detract from the appearance of the decorative textile fabric. A related desirable property in most cases is that the composite surface be lightly colored, white, or non-colored, such that the composite's surface does not show through any lightly colored textile applied thereto and interfere with the aesthetics of the completed panel.
Finally, another desirable characteristic for office panels (and other applications) is that the composite exhibit sound-absorbing acoustical properties. In an office environment, it is desirable that office sounds not be reflected to minimize distractions to employees. As mentioned previously, many office panels contain only a flat woven fabric attached to a metal sheet, resulting in the reflection and repropagation of sound waves, as the sound waves may cause the metal frame or sheet to vibrate and re-transmit the sound. To combat these problems, in some instances, manufacturers use sound absorptive septa between office panels and, in other instances, use sound-absorptive composites as the support for the decorative textile covering.
Thus, there are many substantive issues to be addressed in manufacturing a composite material for use in the office panel industry. The composites described herein address these issues and provide a superior alternative to the existing fiberglass products currently available in the market.